Section 4: Device Descriptions This section of the manual describes the Xinu device drivers available on the distribution tape. Each device driver imple- ments the device independent I/O routines _o_p_e_n, _c_l_o_s_e, _r_e_a_d, _w_r_i_t_e, _s_e_e_k, _g_e_t_c, _p_u_t_c, _c_o_n_t_r_o_l, and _i_n_i_t, for one physical or pseudo-device. While the intuitive meanings of these routines are the same across all devices, each driver defines specific, sometimes device dependent meaning to them. If a particular operation does not make sense for a given device, the driver may choose to return _S_Y_S_E_R_R or _O_K without taking further action.